Load carrying capacity

Pillow (plummer) blocks

SKF pillow block roller bearing units are intended for loads acting perpendicularly toward the support surface. If the bearing unit is supported over its entire base and the loads are purely perpendicular, loads are limited only by the bearing.

If loads acting in other directions occur, be sure that the magnitude of the load is permissible for the housing and the attachment bolts. Guideline values for the safe loads of the housings are provided in table 1, table 2 and table 3. The safe loads have been calculated using a safety factor of 5 against fracture.

If the bearing unit is not supported over its entire base, the load carrying capacity for perpendicular loads may be affected. For additional information, contact the SKF application engineering service.

For a purely axial force, static or dynamic, the permissible load on the housing should not exceed 65% of P180°.

Additional housing support

When the housing is subjected to loads acting parallel to the support surface, it may be necessary to pin the housing to the support surface or to provide a stop to counter the load.

When loads act at angles between 55° and 120°, or when the axial loads are greater than 5% of P180° (table 1, table 2 and table 3), the bearing unit should be pinned to the support surface. The dowel pins should be sufficiently strong to accommodate the loads acting parallel to the support surface.

Flanged units

For the safe loads of flanged units, contact the SKF application engineering service.

Axial holding power

The axial holding power of SKF ConCentra roller bearing units depends on the friction between the shaft and locking device. It is therefore also dependent on the number of set (grub) screws in the mounting collar (table 4).

For collar-mount units, the axial holding power is determined by the size of the set (grub) screws (table 5). The values are valid for unhardened shafts after the set screws have been tightened to the recommended torque value.

When mounted correctly, the bearing units can withstand typical shock loads equivalent to the requisite axial holding force. However, the axial load carrying capacity of the bearing unit can be limited by the bearing.